Common Lung Diseases — Overview and Investigations by lecturio

This article should provide an overview of the main type of diseases that affect the lung. You will find a description of the important diagnostic tests used for investigating respiratory diseases, like general principles, emphasis on lung function testing role and interpretation and examples of diagnostic testing approach for some common presentations.

Table of Contents

• The Big 4 Lung Diseases
• Range of Lung Diseases
• Investigation of Lung Disease
• Different Causes of Large Airway Obstruction
• Large Airway Obstructions: Clues
• References

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Range of lung diseases

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The Big 4 Lung Diseases

1. COPD — most common cause of acute medical admissions
2. Asthma — most common chronic respiratory disease
3. Lung cancer — most common fatal cancer in the Western world for both men and women
4. Pneumonia — most common serious infectious disease

Other common respiratory diseases

• Infectious: tuberculosis, empyema
• Pulmonary emboli
• Bronchiectasis
• Interstitial lung disease and sarcoidosis
• Pleural effusions and pneumothorax
• Obstructive sleep apnea

Range of Lung Diseases

Diseases of the airways

Upper airway obstruction
Lower airway obstruction	Asthma COPD Rarer causes
Airway infection	Acute bronchitis Chronic: bronchiectasis and cystic fibrosis
Airway tumors	Lung cancer: squamous and small cell Rarer tumors, e.g., carcinoid, metastases

Range of lung diseases

Lung parenchyma (alveoli and interstitium)

Infections	Pneumonia Tuberculosis
Interstitial Lung Diseases	Pulmonary fibrosis Sarcoidosis Hypersensitivity pneumonitis Pneumoconiosis Rarer causes
Adult respiratory distress syndrome
Parenchymal tumors	Lung cancer: adenocarcinoma Pulmonary metastases

Circulation

Pulmonary emboli (PE)
Pulmonary hypertension	Cor pulmonale Chronic PEs Other causes
Hemoptysis
Vasculititis

Range of lung diseases

Pleural diseases

Pneumothorax	Transudates Exudates
Pleural infection	Empyema Complex parapneumonic effusions Tuberculosis
Pleural malignancy	Primary: mesothelioma Secondary: metastases

Other

Diseases of physiology	Obstructive sleep apnea Obesity hypoventilation Chest wall/ neuromuscular causes of hypoventilation
Iatrogenic lung disease	Procedure related Caused by drugs Associated with radiotherapy

Investigation of Lung Disease

Different Causes of Large Airway Obstruction

Acute upper airway obstruction

Speed of onset	Cause	Clinical presentation
Sudden	Aspiration of foreign body Mucous plug	Very acute dyspnea and stridor
Acute	Epiglottis/ tonsilar abscess Diphtheria Smoke inhalation Deteriorations of subacute/ chronic causes	Acute dyspnea and stridor Saliva drooling Fever (infective cause)

Chronic upper airway obstruction

Speed of onset	Cause	Clinical symptoms and signs
Subacute/ progressive	Cancer: lung/ larynx/ thyroid Benign tracheal tumors Massive mediastinal nodes Vocal cord paralysis	Progressive/ positional dyspnea Cough Hemoptysis Stridor (can be intermittent) Post obstructive bronchiectasis Dysphagia (esophageal invasion) Pain (malignant causes)
Chronic/ non-progressive	Post-intubation tracheal stenosis Post-infective, e.g., tuberculosis Goiter Previous upper airway surgery Vasculitis Tracheomalacia

Large Airway Obstructions: Clues

1. 

   ‘Squared off’ flow volume loop of tracheal obstruction
   Minimal variability in peak flow/ spirometry
2. Positional symptoms rather than diurnal
3. Inspiratory wheeze (Stridor)
4. Past history of intubation/ tracheal disease
5. Characteristic flow volume loop
6. Fall in PEFR relatively greater than fall in FEV1

Bronchoscopy

• Visual confirmation
• Biopsies to confirm the cause (but can bleed…)
• Treatment as well

Treatment of acute presentation

1. Sit the patient up
2. High flow oxygen or heliox (mixture of oxygen and helium) via mask
3. Intravenous high-dose corticosteroids (reduce edema around obstruction)
4. Nebulized salbutamol and adrenaline
5. Intravenous fluid replacement
6. Potentially urgent intubation or tracheostomy or bronchoscopy intervention

Treatment of chronic obstruction

Chronic—relieve the obstruction by

1. Treat underlying cause if possible
2. Bronchoscopic interventions e.g.
   • Stents
   • Laser ablation
3. Surgical interventions
   • Remove cause
   • Tracheostomy